POS1278 SAFETY AND PHARMACOKINETICS OF IGPRO20 (SUBCUTANEOUS IMMUNOGLOBULIN) AND IGPRO10 (INTRAVENOUS IMMUNOGLOBULIN) IN ADULTS WITH SYSTEMIC SCLEROSIS (SSC) – RESULTS FROM A PHASE 2 TRIAL
Authors: C. P. Denton, O. Kowal-Bielecka, S. Proudman, M. Olesińska, M. Worm, N. Del Papa, M. Matucci-Cerinic, J. Radewonuk, J. Jochems, A. Shebl, A. Krupa, J. Hofmann, M. Gasior
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Systemic sclerosis (SSc) is a severe, progressive multisystem rheumatic disease with high mortality, but without approved disease-modifying treatment to stop or reverse course of disease. Intravenous immunoglobulin G (IgG) may have a positive impact on SSc based upon available literature reports. However, to date, there have been no clinical trials evaluating subcutaneous IgG (SCIG) in SSc. In particular, the impact of pathologically altered skin in SSc on local safety and pharmacokinetics (PK) of SCIG has not been explored yet. <h3>Objectives</h3> The primary and secondary objectives of this trial (NCT04137224) included safety, including local infusion safety, and bioavailability of subcutaneous IgG (IgPro20) in adults with diffuse cutaneous SSc (dcSSc). <h3>Methods</h3> This was a randomized, open-label, crossover study. Adult subjects with dcSSc diagnosis within 5 years from first non-Raynaud's phenomenon and modified Rodnan Skin Score of 15-45 at screening were randomized 1:1 to sequence A (IgPro20, 20% normal human subcutaneous immunoglobulin followed by IgPro10, 10% normal human intravenous immunoglobulin) or sequence B (IgPro10 followed by IgPro20). Each subject was to complete two treatment periods (16 weeks each), with up to 40 weeks (including screening) study duration for an individual subject. Doses received were 0.5g/kg/week split over two sessions for IgPro20, and 2g/kg/4 weeks split over 2-5 days for IgPro10. The primary endpoint was safety of IgPro20, described as treatment-emergent adverse events (TEAEs) and changes in clinical observations. <h3>Results</h3> 27 subjects were randomized, with 13 subjects to sequence A and 14 subjects to sequence B. In total, 25 subjects completed the study. Of 27 treated subjects, 107 TEAEs occurred in 22 subjects (81.5%) over the 36-week study period, the majority of which were mild or moderate. The most common TEAEs (&gt;10% of subjects) by preferred term (PT) were headache (12 events occurring in 6 subjects [22.2%]), COVID-19 (3 events occurring in 3 subjects [11.1%]), diarrhoea (3 events occurring in 3 subjects [11.1%]), and vomiting (3 events occurring in 3 subjects [11.1%]). A total of 10 serious AEs (SAEs) were reported in 6 subjects (Viral infection, Chronic gastritis, Vomiting, Dehydration, Upper gastrointestinal haemorrhage, Chest pain, Myocardial infarction, Myocardial ischemia, Breast cancer, Interstitial lung disease). Among these, one subject experienced 2 SAEs (myocardial ischemia &amp; myocardial infarction) and was discontinued from study treatment. None of the SAEs were considered related to study treatment by the investigator, and no deaths were reported. For IgPro20, 14 infusion site reactions (ISRs) occurred in 5 subjects (19.2%), all were mild or moderate in severity. The most common ISRs were infusion site pain and infusion site swelling (3 events in 2 subjects each, 7.7%). In total, 686 IgPro20 infusions were performed, resulting in an overall ISR rate per infusion of 0.02, ie 2 ISRs per 100 infusions. No ISRs were reported for IgPro10. No clinically relevant trends in vital signs, body weight, clinical laboratory tests, electrocardiograms, or pulmonary function tests were observed. PK profiles and bioavailability in dcSSc subjects were similar to those observed in other approved indications such as Primary Immunodeficiency. Population relative bioavailability of IgPro20, based on dose-normalized, baseline-corrected AUC<sub>0-tau</sub> was 0.761 (90% CI: 0.7033, 0.8232), ie 76.1% compared to IgPro10 (intravenous IgG). <h3>Conclusion</h3> The overall safety profiles of IgPro20 and IgPro10 in subjects with dcSSc were consistent with that in approved indications such as CIDP, including a relatively low ISR rate for IgPro20. PK profiles and bioavailability were also similar to other indications. This study indicates that subcutaneous administration of IgPro20 has acceptable safety, bioavailability and PK profiles in patients with dcSSc. <h3> Acknowledgements</h3> Editorial assistance was provided by Meridian HealthComms Ltd., funded by CSL Behring. <h3>Disclosure of Interests</h3> Christopher P Denton Speakers bureau: Janssen, Boehringer Ingelheim, Consultant of: GSK, CSL Behring, Boehringer Ingelheim, Merck, Roche, Sanofi, Grant/research support from: GSK, CSL Behring, Inventiva, Horizon, Otylia Kowal-Bielecka Speakers bureau: Abbvie, Janssen-Cilag, Boehringer Ingelheim, Medac, MSD, Novartis, Pfizer, Sandoz, Consultant of: Boehringer Ingelheim and Novartis, Grant/research support from: Received congress support from Abbvie, Boehringer Ingelheim, and Medac, Susanna Proudman Speakers bureau: Boehringer Ingelheim, Grant/research support from: Janssen, Marzena Olesińska Consultant of: AstraZeneca, Margitta Worm Consultant of: Novartis Pharma GmbH, Sanofi-Aventis Deutschland GmbH, DBV Technologies S.A, Aimmune Therapeutics UK Limited, Regeneron Pharmaceuticals, Inc, Leo Pharma GmbH, Boehringer Ingelheim Pharma GmbH &amp;Co.KG, ALK-Abelló Arzneimittel GmbH, Kymab Limited, Amgen GmbH, Abbvie Deutschland GmbH &amp; Co. KG, Pfizer Pharma GmbH, Mylan Germany GmbH (A Viatris Company), AstraZeneca GmbH, Lilly Deutschland GmbH and GlaxoSmithKline GmbH &amp; Co. KG., Nicoletta Del Papa Speakers bureau: Janssen Cilag, Boehringer Ingelheim., Marco Matucci-Cerinic Speakers bureau: Biogen, Sandoz, Boehringer Ingelheim, Consultant of: CSL Behring, Boehringer Ingelheim, Grant/research support from: MSD, Chemomab, Jana Radewonuk Shareholder of: CSL Behring, Employee of: CSL Behring, Jeanine Jochems Shareholder of: CSL Behring, Employee of: CSL Behring, Amgad Shebl Shareholder of: CSL Behring, Employee of: CSL Behring, Anna Krupa Shareholder of: CSL Behring, Employee of: CSL Behring, Jutta Hofmann Shareholder of: CSL Behring, Employee of: CSL Behring, Maria Gasior Shareholder of: CSL Behring, Employee of: CSL Behring.